Flame Detector User Manual

General

Description The detector is designed for use where open flaming may be expected. It responds to the light emitted from during combustion. The detector discriminates between flames and other light sources by responding only to particular optical wavelengths and flame flicker frequencies. This enables the detector to avoided false alarms due to such factors as flicking .

Electrical Considerations The flame detector can be connected in many different electrical configurations depending on the application. The detector requires a 24Vdc (14Vmin. to 30Vmax.) supply to operate. The detector can be connected as a two-wire loop powered device increasing its supply current to signal that a flame has been detected. See Fig 8. The supply connections to the detector are polarity sensitive. Also available are volt free contacts from two internal relays RL1 () and RL2 (Fault or pre-alarm). Using the relay contacts connected in a four-wire configuration the detector status can be signalled back to control equipment. See Fig 9. Removing the detector front cover provides accesses the detector terminals and configuration DIL switch. See Fig.4.

Alarm Response Modes The detector is normally configured to latch into an alarm state when a flame is detected. The supply to the detector has to be broken in order to reset the detector. The configuration DIL switch within the detector can be set to place the detector into a non-latching mode. The detector can then also produce proportional analogue current alarm signals i.e. 8-28mA or 4-20mA. In non-latching mode the detector only produces an alarm signal when a flame is in view resetting itself to normal when the flame has gone.

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Application for Flame Detectors Flame detectors are used when detection is required to be:

• Unaffected by convection currents, draughts or wind • Tolerant of fumes, vapours, dust and mist • Responsive to a flame more than 25m away • Fast reacting

The detector is capable of detecting the optical emitted by burning material even non- carbonaceous materials. e.g. Numerous other potential fire sources can be detected such as

Liquids Solids Gases ● Aviation Fuels (kerosene) ● Coal ● Butane ● Ethanol ● Cotton ● Fluorine ● Methylated Spirits ● Grain & Feeds ● Hydrogen ● n-Heptane ● Paper ● ● Paraffin ● Refuse ● Off Gas ● Petrol (gasoline) ● Wood ●

Typical applications examples are:

● Agriculture ● Coal handling plant ● Pharmaceutical ● Aircraft hangars ● Engine rooms ● Power plants ● Atria ● Generator rooms ● Textiles ● Automotive industry ● Metal fabrication ● Transformer stations - spray booths ● Paper manufacture ● Waste handling - parts manufacture ● Petrochemical ● Woodworking

Applications and Locations to Avoid:

● ambient temperatures above 55°C ● large IR sources – heaters, burners, flares ● close proximity to RF sources ● obstructions to field of view ● exposure to severe rain and ice ● sunlight falling directly on the detector optics ● large amounts of flickering reflections ● spot lighting directly on the detector optics

Quantities Required and Positioning of Detectors The number of detectors required and their position depends on:

• the anticipated size of the flame • the distance of the flame from the detector • the angle of view of the flame detector

The flame detector is designed to have a class 1 performance as defined in BS EN54-10:2002 on the high sensitivity setting. That is the ability to detect an n-heptane (yellow) fire of 0.1m² or methylated spirit (clear) fire of 0.25m² at a distance of up to 25m within 30 seconds. The detector can be set to have to a lower sensitivity setting equivalent to class 3 performance. Class 3 performance is defined as detecting the same size fires as for class 1 but at a distance of only 12m.

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In fact, the flame detector will detect fires at distances of up to 40 metres, but the flame size at such distances needs to be proportionally greater in order to be sure of reliable detection. Thus the yellow flickering flame that can be detected at 25m, provided that its size is not less than 0.1m², will have to be 0.4m² in order to be detected at 40metres. In a rectangular room the distance from the flame detector to the fire is calculated by the formula:

Maximum distance = √ L² + W² + H²

In the example shown in fig 1 the room in which the flame detector is to be installed measures 20m x 10m x 5m; the maximum distance from the detector to the flame will therefore be;

FIRE

IR SENS OR

Height Maximum distance = √ 20² + 10² + 5² = 22.9m

Width

Length

Fig 1 Calculation of distance from detector to flame

Field of View The flame detector has a field of view of approximately 90°, as shown in the diagram below.

FIRE

IR SENSO R 90° Cone

Fig 2 Conical field of view of the flame detector

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Centre line of detector

0.4m² flame seen at 40m 0° -15° 15°

0.1m² flame seen at 25m -30° 30°

-45° 45°

-60° 60°

-75° 75°

-90° 90° 0 25m 40m Detector Fig 3 Detector Field of View Plot

The flame detector should be positioned at the perimeter of the room, pointing directly at the anticipated flame or at the centre of the area to be protected. If the detector cannot ‘see’ the whole of the area to be protected, one or more additional detectors may be required.

The flame detector is not affected by normal light sources but should be positioned so that sunlight does not fall directly onto the viewing window.

Detector Window Contamination It is important to keep the detector window clean and checks should be carried out at regular intervals – determine locally according to the type and degree of contamination encountered – to ensure optimal performance of the flame detector. Although the IR detectors can detect flames when the window is contaminated, there may be a reduction of sensitivity as shown in Table 1.

Typical percentage of Contamination normal response Water spray 75% Steam 75% 75% Oil film 86% Salt water film 86% Dry salt deposits 86%

Table 1 IR Detector window contamination UV/IR detectors are more susceptible to window contamination and must be kept clean.

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Detector Interior IR Optics - IR optical flame sensors & filters

Supply ON (Green) - Steady if detector

functioning correctly

Fire (Red) - Indicates a FIRE detected

Test (Yellow) - Indicates detector in test

mode

UV Optics (Option) - UV optical flame sensor if fitted

DIL Switch - Select detector functions

Connection Terminals

Fig 4 Detector with Front Cover removed

Electrical Connections The flame detector has eight connection terminals as show in Fig 5. Removing the front cover of the flame detector accesses the connections. The cable is passed through the gland holes in the base of the detector.

Closes if flames Normally closed detected (N/C) when powered

1 2 3 4 5 6 7 8

+IN -IN +R -R FLAME FAULT (N/O) (N/C) +24Vdc Supply Test Input Relay RL1 Relay RL2 Input

Fig 5 Electrical Connection Terminals

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Connection Terminal Descriptions

Terminal No. Mnemonic Function 1 +IN Power Supply +V. +IN is the power supply input to the flame detector and is normally 24Vdc with respect to terminal 2. The current consumption of detector can be monitored to determine the detector status (Fault, Normal, Pre-alarm, Fire). If the detector is in latching mode then this supply line must be broken in order to reset the detector. A thermal fuse within the detector will blow and break the +IN connection if the detector operating temperature is exceeded. 2 -IN Power Supply 0V. –IN is the return path for the detector supply current. -IN is also internally connected to terminal 4. 3 +R Remote Detector Test Input +V. No connection to +R is necessary if the detector optical and circuit test feature is not required. If 24Vdc is applied to terminals 3 and 4 the detector internal optical test sources will activate to simulate a flame. The detector yellow test LED will flicker to indicate an optical test is progress. The detector will then alarm indicating that the test was successful. 4 -R Remote Detector Test Input 0V. No connection to -R is necessary if the detector optical and circuit test feature is not required. -R is internally connected to terminal 2. 5 Flame Relay RL1. This volt free contact is normally open (N/O) and only closes when a flame has been detected. If the detector is in latching mode (see DIL switch settings) the contact will remain closed RL1 once a flame has been detected. Only when the detector supply +IN is broken will the detector reset and the contact open once again. The 6 contact can be changed to a normally closed (N/C) state by moving the link on JP1 in the rear of the detector. Maximum relay contact ratings: Power=3W, Current=0.25Amp, Voltage=30Vdc. Resistive loads only. 7 Fault or Pre-alarm Relay RL2. This volt free contact is normally closed (N/C) if the detector has no faults and the supply voltage between terminals +IN and –IN is the correct value. If the detector mode is RL2 changed (see DIL switch settings) this relay can be de-energised to reduce the detector current consumption. Alternatively RL2 can be set 8 to provide a pre-alarm fire signal. The normal contact state can be changed state by moving the link on JP2 in the rear of the detector. Maximum relay contact ratings: Power=3W, Current=0.25Amp, Voltage=30Vdc. Resistive loads only.

Table 2 Connection Terminal Descriptions

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Selectable Detector Functions (DIL Switch Settings)

DIL Switch SENSITIVITY Low Class 3 0 1 High Class 1 1 2 3 4 5 6 7 8

Fig 6 DIL Switch with Detector Front Cover Removed (Normal factory settings shown)

Selectable Functions DIL Switch Settings Relay RL2 Function: 1 2 RL2 off (No fault relay) – For lowest detector current consumption. 0 0 RL2 off, or UV pre-alarm, flame or electrical sparks detected. 1 0 RL2 energised on IR pre-alarm 0 1 RL2 detector fault relay (Energised if detector powered and no faults) 1 ~ 1

Detector Supply Current (Detector Status): [-/ = see Output Mode below] 3 4 Low current mode, 3mA / 9mA (RL1 Only), 8mA / 14mA (RL1 & RL2) 0 0 Two-wire current signalling only. No relays operating. 4-20mA, 4/20mA 1 0 Two-wire current signalling 8-20mA, 8/20mA and both relays operating. 0 1 Two-wire current signalling 8/28mA and both relays operating. 1 ~ 1 Output Mode: 5 (-) Proportional analogue supply current. Non-latching fire alarm signalling. (-) 0 (/) Step change, supply current. Latching fire alarm signalling. (/) ~ 1 Response Time: 6 7 Slowest ≈ 8s 0 0 Medium ≈ 4s 1 ~ 0 Fast ≈ 2s 0 1 Faster response times reduce the optical interference immunity. Very Fast ≈ 1s 1 1 Sensitivity: See EN 54-10 8 Low Class 3 0 High Class 1 ~ 1 Factory settings ~

Table 3 DIL Switch Settings

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Theory of Operation

The detector responds to low-frequency The dual (IR²) and triple (IR³) IR (1 to 15 Hz.) flickering IR radiation emitted photoelectric detectors, responding to from flames during combustion. neighbouring IR wavelengths, enable it to IR flame flicker techniques enable the discriminate between flames and spurious sensor to operate through a layer of oil, sources of IR radiation. dust, water vapour, or ice. The combination of filters and signal Most IR flame sensors respond to 4.3µm processing allows the sensor to be used light emitted by flames. By with little risk of false alarms in difficult responding to 1.0 to 2.7µm light emitted situations characterised by factors such by every fire all flickering flames can be as flickering sunlight. detected. Gas fires not visible to the naked eye e.g. hydrogen may also be detected.

Signal Processing

The detector views the flame at particular give the greatest optical false signal optical wavelengths. The more differing immunity as it has the most diverse optical wavelength signals available the selection of optical wavelengths. better the detector is at discriminating The detector processes the optical signal between flames and false optical sources. information to determine if a flame is in So although IR², IR³ and UV/IR² detectors view. This is achieved by comparing the can detect similar sized flames at the signals with known flame characteristics same distances, the UV/IR² detector will stored within the detector.

Flame Detector

Flame Optics Terminals

Signal Input/Output Processing Interface

Fig 7 Block Diagram of the Detector Signal Processing

If the detector has interpreted the optical The detector is constantly checking itself signals as a fire then it produces the to ensure it is performing correctly. If a required output responses. This will be in fault occurs the detector supply current the form of supply current changes and will reduce, the fault relay will de-energise the illumination of the red fire LED. The and the green supply LED will no longer fire relay will also change state if required. illuminate constantly. 8

Connection Information

Control Unit Single pair cable, also see note 1 (Supplied by others)

Flame Detector i + 1 + 24Vdc Normal (Break supply to reset if detector set to latch) - 2 -

NOTE 1 Screened cable should be used with one end of the screen connected to earth. Also care should be taken not to run the detector cable next to power cables. Fig 8 Basic 2 Wire Connection Diagram

The simplest method of connecting the flame detector is in a 2-wire configuration as shown above. With a 24Vdc supply the current (i) drawn by a detector/detectors can be monitored to determine the detector status. The DIL switches within the detector can be set to produce different current values (i) to suit control systems.

Detector Supply Current DIL Switch Setting Comment i @ 24Vdc Normal Alarm Quiescent (Fire) Current Current 1 2 3 4 3mA 9mA 0 0 0 0 Lowest power configuration, RL1 only 4mA 20mA 0 0 1 0 For 4-20mA systems, no relays 8mA 14mA 1 1 0 0 Lowest power configuration & relays 8mA 20mA 1 1 0 1 For 4-20mA systems & relays 8mA 28mA 1 1 1 1 Fire control panels

Table 4 Detector Supply & Alarm Currents

If the detector supply current falls below the normal quiescent current consumption then a fault is present. This could be simply an open circuit cable fault or a fault within the detector possibly due to the detector being taken over its rated temperature. Detectors can be connected in parallel increasing the overall quiescent current required. The alarm current signal will remain the same with the additional quiescent current drawn from other detectors. 9

Control Unit / Interface (Supplied by others)

Flame Detector Two pair cable, also see note 1 24Vdc Normal

+ 1 + (Break supply to reset if detector set to latch) 2 R - - 5 + Fire 6 Zone Relay - 7 Refer to note 2 Fault Relay 8

Flame Detector + 1 2 NOTE 2 - R = To indicate fire to control unit or interface. 5 E.g.: - 470R Fire Relay 6 7 NOTE 3

Fault EOL EOL = End of line device required by some control Relay 8 units. This is required to monitor the cable to the Refer to note 3 detectors and prevent fault indications on the control unit.

Fig 9 4 Wire Connection Diagram

The circuit shown above enables the flame detectors to interface with most type of fire alarm control systems. The fire relay RL1 is used to switch the required alarm load ‘R’ to generate a fire alarm signal. An end of line device ‘EOL’ mounted in the last detector provides the system with the ability to monitor the detector fault relay RL2 and the integrity of the interconnecting cables.

Installation

It is important that the detectors are installed convenience where continuity of a cable in such a way that all terminals and sheath or similar if required. connections are protected to at least IP20 Adjustable mounting brackets and weather with the detector cover fitted. The earth shields are available as shown below. bonding terminals are provided for

Fig 10 Stainless Steel Adjustable Mount Fig 11 Stainless Steel Weather Shield 10

Functional Testing

When 24Vdc power is applied to the detector Alternatively a portable flame sensor test unit the green supply on indicator LED will is available to generate simulated flame illuminate. The fault relay RL2, if selected behaviour and test the detector a few metres with the DIL switch, will energise and the in front of the detector. See Fig 12. contact between terminals 7 and 8 will close. Finally, provided it is safe to do so, carry out If 24Vdc is applied to terminals 3 and 4 or a flame test using a flickering flame source, terminal 3 is linked to terminal 1 the detector such as a portable Bunsen burner. will perform a self-test. It does this by See Fig 13. causing internal optical test sources to A still non-flickering flame will not produce a simulate the behaviour of flames and the response from the detector. detector will alarm.

Fig 12 Portable Flame Detector Test Unit Fig 13 Portable Bunsen Burner

Service & Repairs

Servicing of the system should Only the manufacturer or equivalent be carried out by competent persons familiar authorised body may carry out repairs to the with this type of system, or as recommended flame detectors. In practical terms this by the local regulations in force. means that flame detector may be repaired only at the manufacturers factory.

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This document is the Flame Detector User Manual/2011/Issue 1

Hochiki America Corporation 7051 Village Drive, Suite 100, Buena Park, CA 90621-2268 Phone: 714/522-2246 Fax: 714/522-2268

Information in this guide is given in good faith, but the manufacturer cannot be held responsible for any omissions or errors. The company reserves the right to change the specifications of products at any time and without prior notice.

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